Abstract

Guinea pigs fed a normal diet show the expected diurnal variation in 3-hydroxy-3-methylglutaryl coenzyme A reductase activity. Vitamin C deficiency, however, suppresses the diurnal peak activity of reductase, due to a decrease in active (unphosphorylated) enzyme. Inhibition of reductase is paralleled by both a fall in hepatic cholesterol synthesis and a rise in serum cholesterol. Incubation of normal guinea pig hepatic microsomes with physiologic and supraphysiologic concentrations of sodium ascorbate also leads to a concentration-dependent inhibition of reductase activity. Thus, dietary extremes of vitamin C may exert similar effects on reductase activity and cholesterolgenesis. Moreover, the changes in enzyme activity induced by ascorbic acid appear to be due in part to a direct effect of the vitamin on the microsomally bound enzyme.

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This record was last updated on 07/01/2016 and may not reflect the most current and accurate biomedical/scientific data available from NLM.
The corresponding record at NLM can be accessed at https://www.ncbi.nlm.nih.gov/pubmed/4038887